The incidence of malignant melanoma has increased at an alarming rate over the past few decades, and indications are that the incidence of this deadly disease will continue to rise in the future. As melanoma is known to be refractory to conventional chemotherapy or radiotherapy, several alternative treatment approaches have been used for treatment of this variety of skin cancer. Immunotherapy has been considered potentially useful for melanoma because melanoma has shown certain immunological traits, such as spontaneous regression, infiltration of lymphocytes within the tumor mass, an in vitro demonstration of anti-melanoma specific cellular responses, and evidence of responsiveness to immunomodulators such as interleukins and interferons. (Mukherji B and Chakraborty N G., Immunobiology and immunotherapy of melanoma, Curr. Opin. Oncol. 7:175–184, 1995). For example, immunizing a patient having a melanoma with its own melanoma antigens prepared as a vaccine might induce an anti-tumor immune reaction and thus could cure such a patient from the disease.
The description of one such vaccine can be found in U.S. Pat. No. 4,108,983 to Wallack. This patent describes a first generation melanoma vaccine, Vaccinia Melanoma Oncolysate (VMO), which was derived from melanoma cells lysed by a vaccinia virus (U.S. Pat. No. 4,108,983). This vaccine and modified versions thereof were tested in multiple clinical trials. Although a clinical benefit was seen in several subsets of patients, especially in young male patients with stage III (AJCC) melanoma, the vaccine did not produce a significant benefit for melanoma patients when tested as a surgical adjuvant therapy in a recently completed phase III clinical trial. (Wallack M K, Sivanandham M, et al., Favorable clinical responses in subsets of patients from a randomized, multiinstitutional melanoma vaccine trial, Ann. Surg. Oncol. 3(2):1–8, 1996; Wallack M K, Sivanandham M, Balch C M, et al., A phase III randomized, double-blind, multiinstitutional trial of vaccinia melanoma oncolysate-active specific immunotherapy for patients with stage II melanoma, Cancer 75:34–42, 1995).
U.S. Pat. Nos. 5,635,188 and 5,030,621 both to Bystryn, disclose a vaccine made up of cell surface antigens of melanoma cells that are shed into the culture medium and consequently used as anti-melanoma vaccine.
Similarly, U.S. Pat. No. 5,484,596 to Hanna, Jr. et al. discloses a method of cancer therapy consisting of preparing irradiated tumor cells and injecting them as a vaccine into a human patient.
Although such immunotherapy trials with these vaccines have shown encouraging results in some patients, e.g., partial regression of melanoma, delay in the appearance of recurrent melanoma, and an increase in overall survival as compared to standard therapy or surgery, none of the methods so far have been entirely satisfactory.
During the last two decades, several new immunomodulating cytokines were discovered, and these cytokines have been extensively studied for their therapeutic benefit in patients with cancer. The most studied cytokine is interleukin-2 (IL-2), which has shown some benefit in augmenting immunity against melanoma. The benefit of IL-2 therapy is presumed to be due to the stimulation of T cells, some of which may have become toxic toward tumor cells.
Generally, immunomodulating cytokines such as IL-2 are administered either as a bolus injection or as a low dose continuous infusion (Lotze M T et al., High dose recombinant interleukin-2 in the treatment of patients with disseminated cancers, JAMA 256(22):3117–3124, 1986; West W H et al., Constant infusion of recombinant IL-2 in adoptive immunotherapy of advanced cancers, New Engl. J. Med. 316(15):898–905, 1987). However, bolus injection with a high dose of cytokines generally produces significant toxicity while low dose continuous infusion is inconvenient. A more constant level of cytokine in vivo, similar to that produced by continuous infusion of cytokine, can be achieved using recombinant viruses or bacteria designed to produce cytokines in vivo.
The use of recombinant vectors to induce the production of cytokines in vivo falls within the definition of gene therapy. Some encouraging results have been seen using such vectors. For example, use of the IL-2 gene in recombinant vaccinia virus (rVV) seemed to reduce tumor burden in a mouse melanoma model (Sivanandham M, Scoggin S D, Sperry R G, Wallack M K, Prospects for gene therapy and lymphokine therapy for metastatic melanoma, Ann. Plast. Surg. 28(1):114–118, 1992). In contrast, later studies indicated that recombinant vaccinia with IL-2 had no effect. For example, Qin et al. describe a vaccine that appeared to have some effect with rVV expressing GM-CSF, but not with rVV expressing IL-2. (Qin H, Chatterjee S K, Cancer gene therapy using tumor cells infected with recombinant vaccinia virus expressing GM-CSF, Hum. Gene Ther. 7(15):1853–60, 1996). Similar disappointing results with rVV encoding IL-2 were observed by Shrayer et al. in their melanoma model. (Shrayer D P, Bogaars H, Hearing V J, Wanebo H J, Immunization of mice with irradiated melanoma tumor cells transfected to secrete lymphokines and coupled with IL-2 or GM-CSF therapy, J. Exp. Ther. Oncol., 1(2):126–33, 1996).
Thus, the success of recombinant IL-2 in gene therapy strategies is unpredictable. Initial reports showed objective response rates with single-agent rIL-2 therapy in the range of 15% to 20%; however, the overall response rates in clinics were much lower than originally anticipated. In addition, it appears that co-administration of lymphokine-activated killer (LAK) cells, generated ex vivo with rIL-2, does not enhance the response rates achieved with rIL-2 alone.
For example, U.S. Pat. Nos. 4,863,727 and 5,425,940, both to Zimmerman et al., disclose augmentation of anti-melanoma activity in mammals by administering an effective amount of IL-2 and tumor necrosis factor (TNF), or TNF and interferon (IFN)-beta, or IL-2, TNF, and IFN-beta combinations. These compositions were also suggested to be useful for treating other cancers such as leukemia, lymphoma, mastocytoma, mammary adenocarcinoma, and pharyngeal squamous cell carcinoma.
U.S. Pat. No. 5,066,489 to Paradise et al., discloses treatment of malignant melanoma by combining IL-2 with chemotherapeutic agents.
Rosenberg et al. describe a combination of IL-2 with tumor-infiltrating lymphocytes as a means of providing an immunotherapy to patients with metastatic melanoma (Rosenberg et al., Use of tumor-infiltrating lymphocytes and interleukin-2 in the immunotherapy of patients with metastatic melanoma, New Engl. J. Med. 319:1676–1680, 1988).
Similarly, Dutcher et al. described combining IL-2 with IL-2-activated killer cells as a treatment option for metastatic melanoma. (Dutcher et al., A Phase II study of high-dose continuous infusion interleukin-2 with lymphokine-activated killer cells in patients with metastatic melanoma, J. Clin. Oncol. 9(4):641–648, 1991).
Because of the broad activation nature of T cells, the anti-tumor response generated by IL-2 is not very specific. For that reason, IL-2-based therapy has not proven to be very effective. In addition, the doses of IL-2 required by these IL-2 treatment methods appear toxic to treated patients. (Siegel et al., Interleukin-2 toxicity, J. Clin. Oncology, 9:694–704, 1991). Based on these observations, it was believed that a more specific immune response can be generated by combining IL-2 with tumor specific antigens.
U.S. Pat. No. 5,290,551 to Berd, discloses the treatment of melanoma with a vaccine comprising irradiated autologous melanoma tumor cells conjugated to a hapten and combining the vaccine with IL-2.
U.S. Pat. No. 5,478,556 to Elliott et al., discloses vaccination of cancer patients using tumor-associated antigens mixed with IL-2 and granulocyte-macrophage colony stimulating factor (GM-CSF).
The importance of antigen presenting (APC) or accessory cells in inducing specific cellular immune response was postulated long ago. Among many types of accessory cells are dendritic cells (DC), which are derived from various cell lineages such as bone marrow stem cells, macrophages and lymphocytes. The DC stimulate cytotoxic and helper T-cells by expressing high levels of HLA class I and class II antigens and the T-cell co-stimulatory factors CD80, CD86, ICAM-1 and LFA-3. DC also secrete cytokines such as IL-12, IL-15 and IFN-gamma, which have been shown to be useful for the expansion of stimulated T-cells. DC-based immunotherapies have also been studied in patients with cancers and viral diseases.
To elicit anti-tumor immune response, various cell types have been employed as cellular adjuvants with tumor antigens, and recently several groups have shown that dendritic cells (DC), cultured with tumor cell lysates, synthetic tumor antigens, or peptides purified from tumor cells, induced rather significant anti-tumor immunity in vivo. In all of these approaches, the DC were pulsed with an exogenous source of antigen. Alternative methods were also proposed consisting of genetically engineering DC to express tumor antigens. The expression of tumor antigens by DC is a potent method of inducing tumor antigen-specific responses in vivo. (See Pardoll D M, Cancer vaccines. Nat. Med. 4(5 Suppl): 525–31, 1998). Several melanoma-specific antigens were identified recently, e.g., MART-1/Melan A, gp100, tyrosinase, MAGE-1, MAGE-3, and others. They were accordingly used to elicit anti-tumor immune reaction through presentation via DC. Some studies used not only peptides but unfractionated tumor cell lysates as well (Abdel-Wahab Z, DeMatos P, Hester D, Dong X D, and Seigler H F, Human dendritic cells, pulsed with either melanoma tumor cell lysates or the gp100 peptide (280–288), induce pairs of T-cell cultures with similar phenotype and lytic activity, Cell. Immunol. 186(1):63–74, 1998).
Thus, despite the fact that vaccination with autologous DCs was determined to be safe, the efficacy of such vaccines was not any better than with conventional melanoma vaccines. For example, the objective responses were evident only in 5 out of 16 patients with metastatic melanoma. (Nestle F O, Alijagic S, Gilliet M, Sun Y, Grabbe S, Dummer R, Burg G, Schadendorf D, Vaccination of melanoma patients with peptide- or tumor lysate pulsed dendritic cells, Nat. Med. 4(3):328–332, 1998). This and other similar approaches have failed to improve DC-based vaccines and to enhance the chances of survival of melanoma patients. Despite many studies relating to melanoma vaccine development, so far little real progress has been achieved. Clearly, there is a need for an effective melanoma vaccine useful to slow the progression of, if not cure, melanoma in a higher proportion of patients than in any earlier described vaccines.
U.S. Pat. No. 5,788,963 to Murphy et al., discloses methods and compositions for using human DC to activate T cells for immunotherapeutic responses against primary and metastatic prostate cancer. Other DC based approaches have also been described, e.g. Hsu et al. (Vaccination of patients with B-cell lymphoma using autologous antigen-pulsed dendritic cells, Nat. Med. 2(1):52–58, 1996).
Thus, while multiple approaches to melanoma (and cancer generally) have been undertaken during the last twenty years, and some progress made, the problem has remained. Melanoma continues to be on the rise and refractory to available therapies. (Villikka K, Pyrhonen S. Cytokine therapy of malignant melanoma. Ann. Med. 28(3):227–233, 1996).
Thus, the present invention provides an improved melanoma vaccine that provides a better success rate than the melanoma therapies existing in the prior art.